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KZ305 Rebuild...attempt 25 Apr 2021 08:23 #847408

  • 82KZ305Belt
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When you get the cylinders off you will need a bore gauge to measure the inside diameter to ensure they are still in spec.  I suggest you look for a good machinist who can also remove your valves and clean up the head and cylinders.  If you have an airport nearby there may be a mechanic who does work on the side.
 


An airport coz aluminum? or will any (good) old machine shop do?

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KZ305 Rebuild...attempt 25 Apr 2021 13:03 #847425

  • hardrockminer
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An airport because usually the machinists there are very particular about their work.  Else they become unemployed!
I have a couple of Z1B's restored, an '80 KZ1000LTD restored, a 1981 KZ550 restored and a 2008 KLR 650 for off road fun. My wife has a 2019 Suzuki DR 650 for on and off road.
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KZ305 Rebuild...attempt 25 Apr 2021 14:30 #847440

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Got the head and block off, didn't break anything yet. The head gasket looks fine to me, although maybe the fact that it popped off looking practically brand new says something. The base gasket is gonna be a major PIA to clean off.   Lots of black gunk caked on the piston heads and the valves look like they need some attention. Also some signs of some rubbing on one side of one bore and its corresponding piston wall, but doesn't seem to have scored it too bad...but that's only based on a finger test. All in all, its probably a good thing she's getting her 13,000 mile checkup.

Pics later...

 

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KZ305 Rebuild...attempt 25 Apr 2021 16:52 #847450

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Going boldly where apparently no man has gone before! And if they did, they left no record. Oh my.





Gas tank removed.



tachometer cable removed. They say you should remove the pinion part from the head cover too before installing, but I've read that its not necessary too. Anyway I left it in for now.


Removing breaker plate

 

I guess this is the governor. It took me a long time to figure out that it just slides right off the camshaft. Mental note made.

 

Head/rocker cover off! Thar be ummm... some cammy stuff, Captain!

  

Inside the cover. The cleanest thing we'll see. The tach pinion that we should remove before reinstalling, supposedly, is just left of center.


Do not attempt to remove the camshaft oil seal without this "special tool!!"


 
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KZ305 Rebuild...attempt 25 Apr 2021 17:20 #847452

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Guess its better to put my captions below. Valve springs and the 8 head nuts waiting to come off. These are the only things that come off easy. Wire holding up cam chain 

The camshaft. You take the 2 bolts out of the sprocket to get it loose, and that gives you slack for getting the chain off of it, which is then engaged with the waiting wire or screwdriver lest it fall deep into the abyss of the crankcase.  


Once the head bolts are off (I'm skipping important pictorial steps here, like removing the chain tensioner from the block), lift the head and slide another wire to catch the chain when you remove the first wire... 

the head is off and oh, my...that looks not so good to me but fortunately I'm pretty ignorant. Yes I should have cleaned the exterior better, or at all, before removing it so do as I say not as I do. I was very careful not to let anything fall in. 

I was expecting the head gasket to look...well, not at all like that. 

The block comes up. I had to do some prying on this, unlike the head which I just pulled on. Make sure to use the pry points, one on the left and one on the right. Another wire in place to catch the chain again.


Another look at those pistons...comments? 
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KZ305 Rebuild...attempt 25 Apr 2021 17:23 #847453

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Here's the rubbing one one side of one bore



And on the piston...
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KZ305 Rebuild...attempt 25 Apr 2021 17:33 #847454

  • Nessism
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That scuffed piston seized in the bore.  Not good.

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KZ305 Rebuild...attempt 25 Apr 2021 17:58 #847455

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Couple of the valves. Above is the scuffy side, intake valve is the lower one and looks baaaad even to my ignorant eyes.


 

And the non-scuffed side

Nessism post=847454That scuffed piston seized in the bore.  Not good.

If it seized, I never knew I was running on one cylinder. Which is possible, I suppose....
 
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KZ305 Rebuild...attempt 25 Apr 2021 18:22 #847457

  • ghostdive
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I would say that the damage to the piston/cylinder is not "ideal" but maybe also not "that bad"? I know some will disagree, and I will say that best practice for the most longevity would be boring out (oversized pistons available but probably rare!) or resleeving (yeowch!).

If it passes the fingernail test I would run it - you seem to have gotten it apart pretty easily, another time would be even quicker. 

By the way, the wires to catch the cam chain are a stroke of genius...I never thought of that. 
1982 KZ750 Spectre - Dyna 2.2 coils + 8mm wires, WG coil relay, Mikuni BS34s - 40P/122.5M, Progressive fork springs/KZ900 rear shocks, Vance & Hines 4-1

1982 KZ305 CSR - 18" KZ400 rear wheel

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KZ305 Rebuild...attempt 25 Apr 2021 20:21 #847463

  • Mc Tavish
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That piston is toast, if you are going to reuse it you may as well stop what you're doing now.
Why throw you're time and money at a doomed project.
1978 z650C

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KZ305 Rebuild...attempt 25 Apr 2021 20:28 #847465

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I will tackle the evil circlips tomorrow and take the pistons and bores in Tues or Wed. I think the piston might be toast. Its very slight, but I can feel some wear on it.  Oh well, I may end up exceeding 305 dollars on this but if I can keep it under 500 it'll be worth it just for the edumacation.

Edit: ahh, someone else was calling it toast as I was typing my toasty post. I agree. A toast to us!

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KZ305 Rebuild...attempt 26 Apr 2021 06:17 #847477

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OK, I found a NOS piston but before I go buying one I think I need to get this looked over by the pros. I got a couple recommendations for a machine shop. Since I'm a virgin rebuilder, tell me what I need to know and what I need to ask them to do. Obviously they'll need to hone or rebore the cylinder(s), if possible. What else? Resurfacing? Valve cleanup or grind? Is there else anything I can do at home (ie easy, non-precision work) to save $$? How much should the shop work cost and how do I avoid getting pulled into work I don't need?

 

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